Nathan AirChime K-series Air Horns
History In the early 1950's, Robert E. Swanson (the founder of AirChime Industries) designed a revolutionary new type of airhorn - the K-series. Intended as a replacement for the popular M-series of airhorns, they featured two diaphragms per bell and operated efficiently on much less air pressure. Today, K-series horns are the most popular horns in North America, with the K3H, K3LA and K5LA making up the majority. Types The series started with two variants - the five-chime K5H, and the three-chime K3H. The K5H had five bells - numbers KS-1 through 5. It played a chord of D-sharp minor sixth (D#, F#, A#, C, D#), a very eerie and attention-grabbing chord. The K3H, on the other hand, had three bells - numbers KS-1 through 3. It played a D-sharp minor triad (D#, F#, A#). Due to defects in manufacturing, some K3H's had an odd KS-2 bell that played a G, making a pleasant major triad. With the introduction of Amtrak in the United States, Swanson was approached to design a more pleasant-sounding horn than the eerie D# minor of the K5H. He agreed, and designed the K5LA, which played a very pleasant B-major 7th chord in the first inversion. The K5LA, again, had five bells, but two were modified for the major chord (KS-1, 2, 3A, 4A, and 5). The K5LA was also built on a new "low-profile manifold" mounting, as seen in the photograph. The K3H was also modified into the K3LA, which plays a major chord, with the KS-3 being swapped out for a KS-4A. Today, AirChime produces two more five-chime variants. One is the K5HL, which is a standard K5H but with the KS-5 swapped out for a KS-1L, which plays a low C. The resulting chord is a rather unsettling C, D#, F#, A# and C. The other is the K5LLA, which is pretty much a standard K-5LA but with the KS-5, again, swapped for a KS-1L. The resulting sound is a dischord, playing the notes C, D#, F#, A and B. The K5HL is standard equipment on new GE locomotives, and the K5LLA is standard on new EMD's. Oddly, the K5HL is usually mounted backwards, with four of the bells facing the rear of the locomotive. Some K5HL's are assembled with a KS-3A bell instead the standard KS-3, and are called K5HLL's. Bell Numbers The K-series horns are comprised of the following bells, ordered in pitch from lowest to highest: Bell sets All K-series models are listed below, along with their components and the year they were introduced. Sound Clips Additional Notes When a K5H is built with a low-profile manifold, it's known as a K5L. The same applies for a K5LA on a high-profile manifold - K5HA. A K5LA on a high manifold is very rare, however. Some K3H's have odd KS-2 bells that sound a G, making a pleasant major chord. This is due to an unintended error in manufacturing, but does not affect the volume or efficiency of the horn. K-series bells can be reversed on the manifold, allowing the horn to be used for back-up movements. Earlier in the K-series' production, the horns were available with adjustable "MKS" bells, allowing the operator to change the pitch if desired. This option affected the reliability of the horns somewhat and was soon phased out. The K5H sound sample above is an example of such a horn, tuned perfectly to the chord of D#min6. The K5LLA is also available as a K5LLB, which uses differently-tuned bells to sound like an older M-5.